Electromagnetic assessment of welding processes for packaging of electrical sheets

In this paper, the effect of welding of thin electrical steel sheets is studied and evaluated by experimental magnetic measurements. Welding is a typical method of connecting iron stacks of electrical machines. However, this process deteriorates the magnetic properties of the said electrical sheets, thereby increasing the iron losses and decreasing the magnetization and efficiency of the magnetic core. Two methods of the welding process are assessed, namely spot and line welding. For this assessment an electrical sheet of grade 280-30AP is utilized. The effects of each welding method to the deterioration of the magnetic properties can be characterized in three main categories, namely magnetic short-circuiting of the ring core, thermal degradation and increase of the residual stress distribution inside the material. The results confirm that the eddy-current component of the iron loss is influenced at a different rate as the hysteresis component of the iron loss.